Fresh coat of conductive paint turns walls into interactive sensors

Researchers at CMU and Disney Research have come up with a way to turn regular dumb walls into smart ones

If these walls could talk. A new treatment that smartens up walls might not be about to give your bedroom a voice, but it could give it the ability to track your movements and your use of electronics, thanks to a special electrode-laden coating that turns them into interactive surfaces.

The concept was dreamed up by researchers at Carnegie Mellon University (CMU) and Disney Research who see those big blank surfaces as a little bit wasteful. They started to wonder whether they could instead equip walls with the capacity to do things like sense human touch, pick up gestures and even monitor the use of appliances within a space.

And it turns out with some cheap materials and tools, they could do just that. They started by laying painter's tape across a wall in a criss-cross pattern, and then applying two layers of conductive paint over the top to form a diamond-shaped grid of electrodes on the surface.

The tape was then removed and electrodes were connected to one another, before the wall was then finished with a coat of standard latex paint for protection and aesthetics and hooked up to a custom sensor board. The team's testing showed the diamond grid to be most effective as an electrode pattern.

This electrode wall can be put to use in two ways. The first is as a capacitive touchpad, just like the one you'll find on an iPhone. This means that when somebody touches the wall, their fingers and hands distort the wall's electrostatic field at the point of contact. So, at least in theory, a virtual switch for a light or a thermostat could be placed wherever the user likes, for example. And if the user is close enough to the wall, the system can estimate their movements and potentially recognize gestures as input controls.

The other application is as a massive electromagnetic sensor. Used in this way, the electrode wall acts as a passive antenna to pick up electromagnetic noise from appliances that are switched on in the room. Because different appliances have unique electromagnetic signatures, the system has the capacity to identify which devices are being used and where they are in the room. Similarly, if a person happened to be wearing a device with an electromagnetic signature, the system would be able to track their position.

"Walls are usually the largest surface area in a room, yet we don't make much use of them other than to separate spaces, and perhaps hold up pictures and shelves," said Chris Harrison, assistant professor in CMU's Human-Computer Interaction Institute. "As the internet of things and ubiquitous computing become reality, it is tempting to think that walls can become active parts of our living and work environments."

You can see the researchers demonstrate the interactive wall in the video below.